Yes, you can carry on working on your local branch (let's say it's called feature) and whenever you like do a git rebase master while on feature.  The one point of caution about this is that in general you shouldn't rebase your branch once you've made it public (i.e. pushed it to another repository or allowed someone to fetch it from your repository).  You should only merge your feature branch into master when you consider the feature that you've been developing to be complete and tested.  After that, if you want to add another feature, I would create a new branch for that.
When you run git rebase master while you're on feature, git starts by considering every change in feature that isn't in master.  (This is approximately the set of commits you see from git log master..feature.)  It then tries to reapply the changes introduced by each of those commits onto master, but skipping any that seem to have already been applied.  The implication of this in your situation is that if you've merged feature into master and then made some more commits on feature, it's only those since the merge that will be reapplied in a subsequent rebase.